Hydraulic shock absorber



July 5, 1938. A. B. CASPER HYDRAULIC SHOCK ABSORBER Filed March l5, 1937Mmmm..

HHH

Patented July 5, 1938 UNITED STATES PATENT OFFICE HYDRAULIC SHOCKABSORBER Anthony B. Casper, Buffalo, N. Y., assignor to HoudeEngineering Corporation, Bualo, N. Y., a corporation of New YorkApplication March 15,

2 Claims.

My invention relates to hydraulic shock absorbers, particularly to thoseof the direct acting type in which a cylinder structure and a pistonstructure have relative longitudinal movement for displacement of.hydraulic iiuid under valve control during service of the shockabsorber in connection with vehicle springs.

An important object oi the invention is to produce a shock absorber ofthis type in which the cylinder structure is in the form of a castingproviding the cylinder bore and having longitudinally extending bosseson its outer side which are bored so that one of them may serve as areservoir for hydraulic fluid and the other ymay serve as a passagewayor channel for the flow of displaced hydraulic iluid from one side oithe piston to the other.

A further object is to provide improved valving means in the outer endof the channel for metering the flow during rebound movement of thevehicle springs.

The invention also includes other features of construction andarrangement, and all of the features are embodied in the structuresshown on the drawing, in which drawing:

Figure 1 is a vertical diametrical section of the shock absorber onplane I-I of Figure 2;

Figure 2 is an outer end View of the shock absorber with parts of theshield structure broken away;

Figure 3 is a section of the inner end of a modied shock absorberstructure taken on plane ITI-III of Figure 4; and

Figure 4 is an outer end view of the shock absorbing structure of Figure3.

In the structure shown on Figures 1 and 2 the cylinder wall Iii has aboss II extending longitudinally along one side thereof, and this bossand the cylinder wall may be part of an integral casting. The boss II isbored to provide a fluid reservoir I2 and a fluid flow channel I3respectively. After boring of the boss, the bore I2 forming thereservoir may be closed at its ends by discs I4 and I5, and the boreforming the channel I3 is closed at its inner end as by a disc I6.

The piston structure comprises the piston Il and the piston rod I8extending therefrom through the outer closure plug I9 for the cylinder,the piston rod being secured to a fitting having the eye 2l for securingthe piston structure to a support, such as the chassis of an automotivevehicle. The inner end of the cylinder is closed by a plug 22 havingthreaded engagement therein, the plug having the eye 23 whereby thecylin- 1937, Serial No. 130,849

4(Cl. 18S-88) der structure may be secured to a support such as the axleof an automotive vehicle.

The piston I'I is received on the reduced end 24 of the piston rod andis clamped in place by a nut 25. The piston has ports 26 therethroughcon- 5;, trolled by a valve 21 which may be in the form of an annularplate, the valve being shiftable on the piston with its outward movementlimited by the stop plate 28 fastened between the piston and the pistonrod.

The inner end of the cylinder space is connected with the reservoir I2by a passageway 29. The inner end of the cylinder space is alsoconnected with the inner end of the channel I3 by the passage 30. At itsupper end the cylinder space is connected with the channel I3 by thepassage 3| and between the passages 3| and 30 is interposed valvemechanism V for metering the hydraulic fluid ow during rebound movementof the vehicle spring with which the shock absorber is associated. Thevalve assembly is inserted in the outer end of the channel I3 so as tobe readily accessible for adjustment. The valve assembly comprises thebushing 32 seated against the shoulder 33 in the channel I3, the bushingbeing located a short distance inwardly of the passage 3l. Extendinginto the bushing is the cylindrical valve plug 34 which has the threadedhead 35 engaging the threaded end of channel so that turning of the headwill eiect axial shifting of the valve in the bushing. The valve has thebore 35 which is of such diameter as to leave the valve end in the formof a thin cylindrical shell, the shell having longitudinal slits 3lcooperating with the edge of the bushing 32 to define orifice passages38, the distance between the bushing edge and slits determining the sizeof the oriice passageway and thereby the resistance to the uid flowtherethrough. The edge of the bushing 32 is bevelled so as to present asharp edge to the slits, and this sharp edge with the thin edge wallthrough which the slits extend will cause the oriiice passages to meterthe iiow substantially independently oi viscosity changes in the fluid.

The outer end of the channel I3 is closable by a plug 39. Upon removalof this plug the valve is accessible for adjustment, the valve headbeing provided with a slot for the application of a screwdriver or othersuitable tool whereby 5 the Valve may be readily rotated forlongitudinal shift thereof to increase or decrease the size of theorifice passage.

Describing the operation, during compression movement of the vehiclespring with which the @ook absorber is associated, and inward movementof the piston in the cylinder, the fluid displaced from the inner end ofthe cylinder will flow through the ports Zit past the valve 21 and intothe outer end of the cylinder. Owing to the volumetric differentialcaused by the volume of -the piston rod, the outer part of the cylindercannot accommodate all of the fluid displaced from the innerl end of thecylinder and the surplus fluid Qnows into the reservoir space l2 throughithe pas- Qsageway 29.

During rebound vmovement of the vehicle springs and outward movement ofthe piston, the valve 21 will be closed by the iiuid pressure so thatthe only ow from the outer end of the cylinder to the inner end thereofwill be through the passage 3h the metering orice passage Si the channeli3,Y and the passage 3l). Owing to the volumetric differential caused bythe piston rod, outward movement of the, piston will tend to createsuction in the inner end of the cylinder, but this suction is broken bythe flow of fluid from the reservoir I2 through the passage 29 to theinner end of the cylinder, such inflow also replenishing the cylinderwith fluid to keep it lled up.

At its outer end the outer cylinder head l 9 has the recess 4l for apacking assembly 42 which surrounds the piston shaft and prevents escapeof leakage uid to the exterior of the shock absorber. Any uid leakagepast the piston rod to the recess 4l will be returned to the reservoirby way of the passage 43.

The fitting 2li may support a shield structure 44 which extendstherefrom and surrounds the shock absorber cylinder structure.

lIn the modified arrangement of Figures 3 and 4 the cylinder wall 45 hasbosses 4E and 41 extending longitudinally thereon at diametricallyopposite sides of the wall, the boss 4G being bored to provide thereservoir space 48 and the boss 41 being bored to form the channel 49for the flow of the uid displaced during vehicle spring reboundmovement. The inner end of the cylinder and the inner ends of the bores48 and 43 are closed by an end wall 5t which is integral with thecylinder and boss structure and which has the eye 5| whereby thecylinder structure may be secured to a support as the axle of anautomotive vehicle. The arrangement at y the outer end of the cylinder,including the metering valve for the rebound fluid ow, may be the sameas that shown in Figure 1. The valving through the piston 52 is,however, somewhat modified. The piston receives the reduced inner end 53of the piston rod 54 and is clamped thereto between the nut 55 and theshoulder '56. The piston has passages 5l and 58 therethrough, andbetween the shoulder and the piston is clamped a flexible metal platey59 which overlies the passageway.

The passageway or port 51 is controlled by a check valve such as theball 68 which is held witlnn the passageway by the plate 59. Thearrangement is such that the ball will permit free flow of hydraulic uidthrough the passageway 5'! during in-stroke of the piston in thecylinder but will close the passageway against flow during out-stroke ofthe piston.

'I'he plate 59 does not fully overlap the outer end of the passage 58 sothat there may be restricted flow through the passage during inward andoutward movement of the piston. Should the pressure become excessiveduring vehicle spring compression movement and inward movement of thepiston, the plate will flex for increased flow through ithe passageway58 to assist the flow through Qthe portlr 5l to relieve the pressure.Owing to the volumetric differential at opposite sides of the piston dueto the volume of the;Y piston rod, the outer end of the cylinder cannotreceive all of the fluid dispiaced from the inner end of the cylinderand the surplus iiuid will now through the passage 6l into the reservoir48. The passage 6l may be in the form of an orifice provided-:in thebase of a thimble 62.

During rebound movement of the vehicle spring and outward movement ofthe piston in the cylinder, the iiuid displaced from the outer end dfthe cylinder will iiow through the channel 49 under control of a valvemetering orifice Such as shown in Figure l, the uid entering the lowerend of the cylinder through a passage 53.

A closure plug 64 may be provided for the outer end of the channel 43 sothat access may be had to the metering valve for adjustment thereof.

As shown in Figure 4, the piston rod terminates at its outer end in aneye 65 for securing of the piston structure to a support such as thechassis of an automotive vehicle. The outer end of the reservoir 48 maybe closed as by means of a disc 66.

I thus provide a simple and efiicient shock absorber structure of thedirect acting type in which the valving assembly for metering therebound uid flow is at the upper end of the shock absorber when inservice and is readily accessible for adjustment for setting of theorifice size for the desired shock absorber action.

Although I have shown practical and efficient embodiments of thefeatures of my invention, I do not desire to be limited to the exactconstruction and arrangement shown, as changes and modications may bemade without departing from the scope of the invention.

I claim as follows:

In a hydraulic shock absorber of the class described, a cylinderstructure, a piston structure, a check valve controlled port in saidpiston structure open to fluid flow during inward movement of the pistonstructure but closed to fluidflow during outward movement of the pistonstructure, another port through said piston structure, and a flap valveanchored to the piston structure andpartially overlying said other partfor normal closure thereof except for a restricted passage, said valveiiexing for increased ow through said other port when said pistonstructure is moving inwardly.

2. In a hydraulic shock absorber of the direct acting type, a cylinderstructure, a piston structure, a port through said piston structure, acheck valve seated to close said port during outward movement of thepiston structure but unseating for opening of said port during inwardmovement of the piston structure, another port through said pistonstructure, a resilient annular valve disk anchored at its inner edge tothe piston structure and partially overlying said ports whereby toprovide a stop for limiting the unseating movement of said check valveat one port and to provide a restricted passageway for ow of fluidthrough said other port during outward movement of the piston structure,said valve yielding for greater flow through said other port duringinward movement of the piston structure.

ANTHONY B. CASPER.

